------In 16-man Normal and HM, the Orobirds are missing (supposedly 8-man HM too, but I've heard mixed results on this so not sure!) and maybe if you find the Orobirds, you find a nest/an egg?
I can 100% confirm that the Orobirds are missing from their normal SM location in 8-man HM. Exploring the instance has still not been fruitful, unfortunately. I'm wondering if they might make it drop from Kephess when Nightmare Mode comes out, but that's pure speculation on my part.
I've set up a Google Alert for "orochick" and both "wondrous egg" and "wonderous egg", so hopefully I will see any information that does surface very quickly
I've also just asked on Reddit
if anyone knows how to get it.